Anatomy of a Wheel

Don’t be left in the dust when it comes to shopping for wheels, educate yourself to better understand terms like ‘How many spokes’ or ‘center bore’.


The biggest part of a wheel is the structure or barrel. This looks like a tube and might be short or long. This part is what allows a tire to be fitted on, usually knowing the size of the barrel Is not needed as Original sizes stay the same.


The outer lip if the wheel is the as the name states, the outer edge. The outer lip is the part that is most likely bent when a wheel hits a pothole and the most repairable area. Technically the lip can be as big or deep until it meets the face of the wheel.

Valve Stem

A valve stem is where tire pressure is monitored, a small 1-2 inch metal stem somewhere on the outer edge of the wheel. Tire valve stems come in three different types depending on the type of vehicle: Snap-in, Snap-in for High Pressure, and metal clamp in.


Besides the size, spokes are what make individual wheels unique and stand out from each other, or the most “cosmetic” aspect of wheels and rims. For example, 90% of steel rims don’t have spokes, just full on metal. Spokes are the pieces that hold the wheel together from the outer edge to the center, and the designs can be super basic or intricate. Spoke design usually begins with how many there are, how thick they are, and how they meet the edge of the wheel. For example, if they veer out to a ‘Y’ shape, they are called Y spokes.

Center Cap

Smack dab in the center of the wheel is the center cap, where the spokes touch. The center cap is removable, except on steel rims. The purpose of the cap is to cover the hole in the center and protect the lug nuts. A wheel can move without a cap with no problem, generally, a center caps purpose is to have the OEM logo and make the wheel look complete.

Lugs Holes/Nuts

Lug holes are the holes that the center cap covers, in which lug nuts go into to hold the wheel together. Wheels can have 4, 5, 6, or 8 lug holes. The term ‘Bolt pattern’ is the measurement from one bolt Is the opposite one across.


This is the big hole in the back of a wheel so it can slide onto the axle of the vehicle. A correct fitting center bore is extremely important, that’s why when buying aftermarket parts exact measurements and specs are key!